独柱墩曲线箱梁桥抗倾覆稳定性研究

发布时间：2018-02-01 01:13

本文关键词： 曲线梁桥独柱墩抗倾覆稳定性支座偏心曲率半径　出处：《郑州大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着我国城市现代化脚步的加快,城市人口密度的不断提高,随之而来的就是城市交通拥堵问题,使得出行不便。为了缓解道路堵塞问题并提高出行质量,大量的互通立交桥和高架桥应运而生。由于曲线桥的桥型更能适应复杂的城市地形地貌以及流顺的车辆行驶,使其备受相关设计者青睐。相对于直线桥而言,“弯扭耦合”是曲线桥最大的特点之一,即使在自重作用下也会出现这样的现象。我国相关设计者更加侧重于桥梁的抗弯抗剪等受力性能上面,对于曲线桥的偶然偏心作用关注不足,而近些年来却常有桥梁倾覆事故的发生。结合工程,建立不同曲率半径和不同支座偏心下的有限元模型,通过加载汽车荷载以研究三等跨独柱墩曲线箱梁桥的抗倾覆性能,主要得到以下结论:(1)当中墩支座位于联端外侧支座的连线的内侧时,倾覆轴线为联端外侧支座的连线;当中墩支座位于联端外侧支座的连线的外侧时,倾覆轴线为两中墩支座的连线。当联端外侧支座和中墩支座接近位于一条直线上时,支座偏心距对倾覆轴线的选取方法具有较大的影响。(2)支座偏心对曲线桥联端内外侧支反力影响明显。随着偏心距的增加,联端外侧支座支反力在不断减小,联端内侧支座支反力在不断增大;支座偏心距的大小对中墩支反力的变化影响较小。(3)根据《公路钢筋混凝土及预应力混凝土桥涵设计规范(征求意见稿)》中的公式计算,曲率半径偏小时,支座偏心对抗倾覆安全系数影响较大;曲率半径偏大时,支座偏心对抗倾覆安全系数影响较小。这是由于在偏心距增大时,联端支反力力矩增加量和中墩支反力力矩减少量基本一样,所以在公式运算过程后对安全系数影响较小。(4)通过征求意见稿中的公式计算出的抗倾覆安全系数可以看出:车道荷载作用下的抗倾覆安全系数整体小于车辆荷载作用下的抗倾覆安全系数,所以考虑最不利情况,在进行上部结构整体抗倾覆验算时宜采用车道荷载。(5)合理的预偏心下,曲率半径的增大使得抗倾覆安全系数值呈现先减小后增大的趋势。所以在桥梁设计时应尽量避免抗倾覆安全系数较低值所对应的曲率半径。
[Abstract]:With the acceleration of the pace of urban modernization and the continuous increase of urban population density, it is followed by the problem of urban traffic congestion, which makes travel inconvenience. In order to alleviate the problem of road congestion and improve the quality of travel. A large number of interchange bridges and viaducts emerge as the times require. Because the curved bridge can adapt to the complex urban topography and the smooth traffic, it is favored by the designers. Compared with the straight line bridge. "bending and torsional coupling" is one of the most important characteristics of curved bridges, even under the action of self-weight, this phenomenon will also occur. The designers of our country pay more attention to the mechanical properties of bridges, such as flexural and shear resistance. The accidental eccentricity of curved bridge is not paid enough attention, but in recent years, bridge overturning accidents often occur. Combined with engineering, the finite element model of different curvature radius and different bearing eccentricity is established. By loading the vehicle load to study the anti-overturning performance of the third class single-column pier curved box girder bridge, the following conclusions are obtained: 1) the middle pier support is located in the inner side of the line of the outer end support. The overturning axis is the line of the outer support of the coupling; When the middle pier support is located on the outer side of the line of the coupling side support, the overturning axis is the connection between the two middle pier supports. When the coupling outside support and the middle pier support are located in a straight line. The eccentricity of bearing has a great influence on the selection of overturning axis. (2) the eccentricity of support has obvious influence on the reaction force of the inner and outer side of the curve bridge end, and with the increase of eccentricity. The reaction force of the lateral support is decreasing and the reaction force of the inner support is increasing. The influence of support eccentricity on the reaction force of the middle pier is small. 3) the formula is calculated according to the formula in the Design Code for Highway reinforced concrete and Prestressed concrete Bridges and culverts (draft for soliciting opinions). When the radius of curvature is small, the safety factor of eccentricity of bearing against overturning is more important. When the radius of curvature is too large, the influence of eccentricity on overturning safety factor is small, which is due to the increase of counterforce torque of end support and the decrease of reaction moment of middle pier when eccentricity increases. Therefore, the effect on the safety factor is small after the formula operation. 4). Through the formula in the draft of soliciting comments, we can see that the safety factor of anti-overturning under the action of driveway load is less than that of the anti-overturning safety factor under the action of vehicle load. Therefore, considering the most adverse situation, under the reasonable pre-eccentricity, the overall overturning check of the superstructure should be carried out under the reasonable eccentricity of driveway load. The increase of curvature radius makes the value of anti-overturning safety factor decrease first and then increase, so the curvature radius corresponding to the lower value of anti-overturning safety factor should be avoided in bridge design.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U448.213;U441

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